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The 32-core is a stupid, pointless CPU because of the disabled channels.
This is an exercise in benchmark showboating. I don't care about people circle jerking over theory that has little application or relevance to the real world. Wall Street clearly didn't understand why the RX video cards were such a success, nor did they understand the oncoming market landslide that the first generation of Zen and EPYC represented. Now they're all freaking about AMD, these dilettantes who understand nothing but the current stock price, and not why that stock price came to be. This should have been their reaction 18 months ago-- I was right here predicting that future.Anandtech said:
When some cores are directly connected to memory, such as the 2950X, all of the cores are considered equal enough that distributing a workload is a fairly easy task. With the new processors, we have the situation on the right, where only some cores are directly attached to memory, and others are not. In order to go from one of these cores to main memory, it requires an extra hop, which adds latency. When all the cores are requesting access, this causes congestion.
In order to take the full advantage of this setup, the workload has to be memory light. In workloads such as particle movement, ray-tracing, scene rendering, and decompression, having all 32-cores shine a light means that we set new records in these benchmarks.
In true Janus style, for other workloads that are historically scale with cores, such as physics, transcoding, and compression, the bi-modal core caused significant performance regression. Ultimately, there seems to be almost no middle ground here – either the workload scales well, or it sits towards the back of our high-end testing pack.
Part of the problem relates to how power is distributed with these big core designs. As shown on page four, the more chiplets that are in play, or the bigger the mesh, the more power gets diverted from the cores to the internal networking, such as the uncore or Infinity Fabric. Comparing the one IF link in the 2950X to the six links in 2990WX, we saw the IF consuming 60-73% of the chip power total at small workloads, and 25-40% at high levels.
In essence, at full load, a chip like the 2990WX is only using 60% of its power budget for CPU frequency. In our EPYC 7601, because of the additional memory links, the cores were only consuming 50% of the power budget at load. Rest assured, once AMD and Intel have finished fighting over cores, the next target on their list will be this interconnect.
But the knock on effect of not using all the power for the cores, as well as having a bi-modal operation of cores, is that some workloads will not scale: or in some cases regress...
This is the point where I mention if we would recommend AMD’s new launches. The 2950X slots right in to where the 1950X used to be, and at a lower price point, and we are very comfortable with that. However the 2950X already sits as a niche proposition for high performance – the 2990WX takes that ball and runs with it, making it a niche of a niche. To be honest, it doesn’t offer enough cases where performance excels as one would expect – it makes perfect sense for a narrow set of workloads where it toasts the competition. It even outperforms almost all the other processors in our compile test. However there is one processor that did beat it: the 2950X.
My crystal ball is unimpressed. AMD's future, especially now that China has their IP, is less certain and bright than it was 18 months ago. Zen2 is a solid sequel, but not the game-changer Zen1 was. Those buying now missed the bus. There might be some short term gains, but long term, for GPUs, NVIDIA is the sure thing, and for CPUs, it's all about the lower-cost ARM manufacturers.
